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(No Model.)

M. B. KIRKER.

WHIFFLETRBE. No. 392,273. Patented Nov. 6, 1888.

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NITED STATES PATENT MILTON B. KIRKER, OF IITTSBURG, PENNSYLVANIA, ASSIGNOR, BY MESNE ASSIGNMENTS, TO THE PITTSBURG TUBULAR STEEL VVHIFFLETREE COM- PANY, OF SAME PLACE.

WHIFFLETREE.

SPECIFICATION forming part of Letters Patent No. 392,273, dated November 6, 1888.

Application filed February 24, 1887. Renewed October 10, 1888. Serial No. 287,784. (No model.)

To aZZ whom it may concern.-

Be it known that I, lVIILTON B. KIRKER, residing at Pittsburg, in the county of Allegheny and State of Pennsylvania, a citizen of the United States, have invented or discovered certain new and useful Improvements in Singletrees and Doubletrees, of which improvement the following is a specification.

In the accompanying drawings, which make IO part of this specification, Figure 1 is a view in side elevation of a singletree embodying my invention. Fig. 2 is a similar view of a doubletrec. Fig. 3 is a longitudinal section through the doubletree. Fig. 4 is a transverse section on the line a: 00, Fig. 2.

The invention herein relates to certain improvements in the manufacture of singletrees, doubletrees, and other like articles; and it consists, generally stated, of a tube tapering from 2c itsmiddle portion toward each end, and hav ing suitable fittings secured therein in such a manner as to avoid all liability of their becoming loosened under ordinary conditions of wear or use or by reason ofexposu re to atmospheric influences.

Singletrees and doubletrees are ordinarily formed of some tough wood, and the fittings therefor are usually secured by shrinking them upon the wood or by means of bolts or rivets.

0 The latter method of securing the fittings- 0., by bolts or rivets-is objectionable, not only on account of the weakening of the wood by the holes formed by the rivets, but also on account of the bolts or. rivets becoming loose.

3 5 In shrinking the fittings on they are heated to approximately a dark cherry-red,then slipped onto the wood, and rapidly cooled by the application of water. This manner of securing the clips is temporarily uuobjectionable; but as the hot metal chars the surface of the wood in contact therewith the blows and other rough usage to which these articles are subjected cause a comminution or pulverization of the charred surfaces and a consequent loosening 5 and dropping off of the fittings. Singletrees and doubletrees have also been made of metal tubes, the fittings therefor being either secured to the tubes by bolts or rivets or else forged thereon, both methods being objectionable on account of the time and labor required therefor.

In the practice of my invention I take a wrought-metal tube or pipe of suitable length and diameter, and by means of suitable tools gradually taper it from its middle portion to- 5 5 ward its ends, thus forming the bar 1. The central fitting, 2, formed of cast-iron and malleableized, the internal diameter of the part thereof designed to encircle the bar being a little less than the external diameter at its middle portion, is heated to a cherry-red, thereby expanding it, and is slipped over one end of the bar, and, being adjusted accurately in place on the middle portion of the bar, is cooled. The contraction of the fitting will cause it to adhere so firmly to the bar that nothing short of its destruction or a reheating can move it from place. The tapering of the bar from its center to the ends is expedient for facilitating the slipping on of the middle fitting, for the reason that as the fitting is only a small fraction of an inch larger than the bar, even when expanded,it would be liable to catch on the bar at some point other than that desired were the bar of uniform diameterthroughout its'entire length. I prefer to leave a portion, 3, at the middle, equal in length to the width of the fitting, flat, and thereby avoid the necessity of giving a double taper to the inner surface of the'fitting, in order to get a uniform bearing on the bar,as would be necessary if the tapering surfaces met and formed an angle at the middle of the bar. The end fittingsA, having their sockets tapering to correspond to the taper of the bar, are secured in 8 5 placejn a similar manner.

As I do not wish to limit myself to any particular shape or construction of fitting, a further description of the fitting seems unnecessary. By the term fitting, as hereinbefore used, I mean those devices which are placed on the middle and ends of singletrees and the draft-bars of doubletrees for the purpose of connecting the singletrees to the draft-bars or of connecting the tugs or chains of a harness 5- to the singletrees.

Neck-yokes for wagons which are very simi lar to singletrees can readily be made in the manner above deseribed,and are therefore eonhination,a metal tube having a straightmiddle sidered as within the scope of the invention portion, and tapering thence each way to its herein. ends, and malleable east-iron fittings shrunk I claim herein as my inventionupon the metal tubes, substantially as set forth. 5 1. A singletree or draft-bar having,in eom- Intestimony whereof I have hereunto set 15 biuation,a metal tube tapering fromits middle my hand. toward the ends and malleable east-iron fit- MILTON I3. KIRKER. tings shrunk upon the metal tubes, substan- Witnesses: tially as set forth. DARWIN S. WoLoo'r'r,

IO 2. A singletree or draft-bar l1aving,in eom- V. B. CORWIN. 

